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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/devicetree/bindings/ABI.txt
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
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+
+ Devicetree (DT) ABI
+
+I. Regarding stable bindings/ABI, we quote from the 2013 ARM mini-summit
+ summary document:
+
+ "That still leaves the question of, what does a stable binding look
+ like? Certainly a stable binding means that a newer kernel will not
+ break on an older device tree, but that doesn't mean the binding is
+ frozen for all time. Grant said there are ways to change bindings that
+ don't result in breakage. For instance, if a new property is added,
+ then default to the previous behaviour if it is missing. If a binding
+ truly needs an incompatible change, then change the compatible string
+ at the same time. The driver can bind against both the old and the
+ new. These guidelines aren't new, but they desperately need to be
+ documented."
+
+II. General binding rules
+
+ 1) Maintainers, don't let perfect be the enemy of good. Don't hold up a
+ binding because it isn't perfect.
+
+ 2) Use specific compatible strings so that if we need to add a feature (DMA)
+ in the future, we can create a new compatible string. See I.
+
+ 3) Bindings can be augmented, but the driver shouldn't break when given
+ the old binding. ie. add additional properties, but don't change the
+ meaning of an existing property. For drivers, default to the original
+ behaviour when a newly added property is missing.
+
+ 4) Don't submit bindings for staging or unstable. That will be decided by
+ the devicetree maintainers *after* discussion on the mailinglist.
+
+III. Notes
+
+ 1) This document is intended as a general familiarization with the process as
+ decided at the 2013 Kernel Summit. When in doubt, the current word of the
+ devicetree maintainers overrules this document. In that situation, a patch
+ updating this document would be appreciated.